8 i 5 0 File: 17G

D.P.

ELLSWORTH AFB

SOUTH DAKOTA

I I

ADMINISTRATIVE RECORD

COVER SHEET

AR File Number _/

II I 1
File:

::- 81 5 1 _t5

Final

Record of Decision for

Remedial Action at Operable Unit 1

Ellsworth Air Force Base, South Dakota

United States Air Force

Air Combat Command

Ellsworth Air Force Base

April 1996

AF Project No.: FXBM 94-7002
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Final Record of Decision Operable Unit 1

__ , EIlsworthAir Force Base, South Dakota

TABLE OF CONTENTS

Chapter Page

1.0 DECLARATION FOR THE RECORD OF DECISION ................................................................. 1-1

1.I SITE NAME AND LOCATION ............................................................................................ 1-1

1,2 STATEMENT OF BASIS AND PURPOSE .......................................................................... I-1

1.3 ASSESSMENT OF THE SITE .............................................................................................. 1-1

1,4 DESCRIPTION OF SELECTED REMEDY .......................................................................... I-I

1.5 STATUTORY DETERMINATION ..................................................................................... 1-2

1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY ................................. 1-2

2.0 DECISION SUMMARY .................................... :::............................................. -............................ 2-1

2.1 SITE NAME AND LOCATION ............................................................................................ 2-I

2.2 OPERABLE UNIT 1 (OU-1) DESCRIPTION/HISTORY AND

REGULATORY OVERSIGHT ACTIVITIES ....................................................................... 2-1

2.2.1 Description/History ................................................................................................. 2-1

2.2.2 Regulatory Oversight Activities ............................................................................... 2-2

2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION .......................................................... 2-3

2.4 SCOPE AND ROLE OF RESPONSE ACTION .................................................................... 2-4

2.5 SITE CHARACTERISTICS .................................................................................................. 2-5

2.5.1 Soils ....................................................................................................................... 2-5

2.5.2 Sediment ....................................... 2-6

2.5.3 Ground Water ......................................................................................................... 2-6

2.5.4 Surface Water ................................................................................................. i....... 2-7

2.6 SITE RISK SUMMARY ....................................................................................................... 2-7

2.7 DESCRIPTION OF ALTERNATIVES ................................................................................. 2-9

2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES ............................... 2-10

2.8.1 Overall Protection of Human Health and the Environment ...................................... 2-11

2.8.2 Compliance with ARARs ...................................................................................... 2-11

2.8.3 Long-Term Effectiveness and Permanence ............................................................. 2-14

2.8.4 Reduction of Toxicity, Mobility, and Volume Through Treatment ......................... 2-14

2.8.5 Short-Term Effectiveness ...................................................................................... 2-15

2.8.6 Implementability .................................................................................................. 2-15

2.8.7 Cost ...................................................................................................................... 2-15

2.8.8 State Acceptance ................................................................................................... 2-17

2.8.9 Community Acceptance ........... ; .2-17

2.9 SELECTED ALTERNATIVE ............................................................................................. 2-17

2.10 STATUTORY DETERMINATIONS .................................................................................. 2-20

2.10. I Protection of Human Health and the Environment .................................................. 2-20

2.10.2 Compliance with ARARs ...................................................................................... 2-21

2.10.3 Cost Effectiveness ................................................................................................. 2-21

2.10.4 Utilization of Permanent Solutions and Alternative Treatment

Technologies to the Extent Possible ...................................................................... 2-21

2.10.5 Preference for Treatment as a Principal Element .................................................... 2-21

2.11 DOCUMENTATION OF SIGNIFICANT CHANGES ........................................................ 2-21

3.0 LIST OF ACRONYMS AND ABBREVIATIONS ......................................................................... 3-I

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Appendix A Figures

Appendix B Responsiveness Summary

LIST OF FIGURES

Figure 2-1 Area Location Map

Figure 2-2 Site Map

Figure 2-3 Operable Unit 1

Figure 2-4 Area of Attainment for Source Area Soils

Figure 2-5 Area of Attainment for Ground Water

LIST OF TABLES

Table 2-1 OU-1 Cleanup Goals - Ground Water

Table 2-2 OU-1 Cleanup Goals - Soils

Table 2-3 Evaluation of Federal and State ARARs That May Apply to OU-1, Ellsworth

AFB, South Dakota

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1.0 DECLARATION FOR THE RECORD OF DECISION (ROD)

1.1 SITE NAME AND LOCATION

• Operable Unit 1 (OU-1), Abandoned Fire Protection Training Area, Ellsworth Air Force

Base (EAFB), National Priorities List Site.

• Meade and Pennington Counties, South Dakota

1.2 STATEMENT OF BASIS AND PURPOSE

This decision document describes EAFB's selected remedial action for Operable Unit 1 (OU-1),

in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act

of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986

(SARA), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).

This decision is based on the contents of the Administrative Record for OU-1, EAFB. The United

States Environmental Protection Agency (EPA) and the South Dakota Department of

Environment and Natural Resources (SDDENR) concur with the selected remedial action.

1.3 ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from OU-1, if not addressed by

implementing the response action selected in this Record of Decision (ROD), may present an

imminent and substantial endangerment to public health, welfare, and the environment

1.4 DESCRIPTION OF SELECTED REMEDY

Twelve contaminated areas, delineated as operable units (OUs) for investigative purposes, have

been identified at EAFB. This ROD is for a remedial action at OU-1.

The selected alternative, source area soil and ground-water treatment, includes the following

major components:

• Continued operation of the interim remedial action (IRA) which consisted of

contaminated ground-water removal, soil vapor extraction (SVE), and treatment;

• Installation of additional SVE wells within the historical bum-pit area to be added to the

existing IRA SVE system;

• Removal of contaminated ground water using additional ground-water wells and

collection trenches to be added to the IRA ground-water recovery system;

• Treatment of ground water at the existing IRA treatment plant;

• Institutional controls for the area;

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• Long-term monitoring; and,

• Long-term operation and maintenance of equipment.

1.5 STATUTORY DETERMINATION

The selected remedy is protective of human health and the environment, complies with Federal

and the State of South Dakota requirements that are legally applicable or relevant and appropriate

to the remedial action, and is cost-effective. This remedy utilizes permanent solutions and

alternative treatment (or resource recovery) technologies, to the maximum extent practicable for

OU-1.

A review will be conducted no less often than every five years after signing of the ROD to ensure

that the remedy continues to provide adequate protection of human health and the environment.

1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY

BRETT M. DULA Date

Lie_enant General, USAF

• Vi Commander

A_i K W MCGRAW ng Regional Administrator

kI_ E ironmental Protection Agency Region 8

NETTIE H. lvI'_ERS, Se_lary Date

Department of Environnie_ and Natural ResourCeS

State of South Dakota

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• Long-teJm monitoring; and,

• Long-term operation and maintenance of equipment.

1.5 STATUTORY DETERMINATION

The selected remedy is protective of human health and the environment, complies with Federal

and the State of South Dakota requirements that are legally applicable or relevant and appropriate

to the remedial action, and is cost-effective. This remedy utilizes permanent solutions and

alternative treatment (or resource recovery) technologies, to the maximum extent practicable for

OU-1.

A review will be conducted no less often than every five years after signing of the ROD to ensure

that the remedy continues to provide adequate protection of human health and the environment.

1.6 SIGNATURE AND AGENCY CONCURRENCE ON TIlE REMEDY

BRETT M. DULA Date

Lieutenant General, USAF

Vice Commander

JACK W. MCGRAW Date

Acting Regional Administrator

US Environmental Protection Agency Region 8

NETTIE H. MYERS, Secretary Date

Department of Environment and Natural Resources

State of South Dakota

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2.0 DECISION SUMMARY

2.1 SITE NAME AND LOCATION

EAFB is a U.S. Air Force Air Combat Command (ACC) installation located 12 miles east of

Rapid City, South Dakota, and adjacent to the small community of Box Eider (Figure 2-1).

EAFB covers approximately 4,858 acres within Meade and Pennington counties and includes

runways and airfield operations, industrial areas, and housing and recreational facilities (Figure 2-

2). Open land, containing a few private residences, lies adjacent to EAFB on the north, south,

and west, while residential and commercial areas lie to the east of the Base.

2.2 OPERABLE UNIT 1 (OU-I) DESCRIPTION/HISTORY AND REGULATORY

OVERSIGHT ACTIVITIES

2.2.1 Description/History

Ellsworth Air Force Base (EAFB) was officially activated in July 1942 as the Rapid City Army

Air Base, a training facility for B-17 bomber crews. It became a permanent facility in 1948 with

the 28th Strategic Reconnaissance Wing as its host unit. Historically, EAFB has been the

headquarters of operations for a variety of aircraft, as well as the Titan I Intercontinental Ballistic

Missile, and the Minuteman I and Minuteman II missile systems. The Air Force has used EAFB

for support, training, maintenance, and/or testing facilities. Presently, the 28th Bombardment

Wing (B-1B bombers) is the host unit of EAFB.

OU-1 consists of the former Fire Protection Training Area (FPTA), Pond 001, and a portion of

the drainage channel which leads into Pond 001. The former FPTA is approximately ten acres in

size and is located in the southwestern segment of EAFB (Figure 2-3). The FPTA was operated

by the EAFB Fire Department at this location from 1942 to 1990. The location of the burn area

within the former FPTA has changed several times over the years. Aerial photographs of EAFB

dated 28 May 1952, 8 October 1954, 25 August 1962 and 19 June 1968 show numerous areas of

staining presumed to be a result of fire training activities within the former FPTA. The training

exercises conducted at the FPTA involved simulation of aircraft fires and spills. Various types of

fuels, oils, and solvents were dispersed within the burn-pit area and subsequently ignited and then

extinguished.

The topography at OU-1 is characterized by a local topographic high in the area where fire

training was conducted, which is bounded on the southwest and southeast by converging drainage

channels. Pond 001 was included in OU-1 to determine if it contained contaminants which

originated at the former FPTA.

A shallow aquifer has been identified at depths of 10 feet to 50 feet beneath the ground surface.

This ground water is classified as having a beneficial use as a drinking water supply suitable for

human consumption (ARSD Chapter 74:03:15, Groundwater Quality Standards). The shallow

aquifer may also discharge to the surface.

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Deeper bedrock aquifers also exist beneath EAFB, These deeper aquifers are separated from the

shallow aquifer by 800 feet of low-permeability clays and silts. In the past, EAFB utilized these

deeper aquifers for its water supply. Presently, EAFB obtains its potable water from the Rapid

City Municipal Distribution System.

2.2.2 Regulatory Oversight Activities

Environmental investigation activities at EAFB were initiated by the Air Force in 1985 through an

Installation Restoration Program (IRP) Phase I Installation Assessment/Records Search and Phase

II, Confirmation/Quantification. The Phase I study, dated September, 1985, identified a total of

17 locations at EAFB where releases involving hazardous substances potentially occurred.

In Phase II of the IRP investigation, field activities included soil vapor surveys, geophysical

surveys, surface and subsurface soil sampling, ground-water sampling, ground-water hydrologic

testing, and ecological investigations.

On August 30, 1990 (55 Federal Register 35509), EAFB was listed on the U.S. EPA's National

Priorities List (NPL). A Federal Facilities Agreement (FFA) was signed in January 1992 by the

Air Force, EPA, and the State of South Dakota (State) and went into effect on April 1, 1992.

The FFA establishes a procedural framework and schedule for developing, implementing, and

monitoring appropriate response actions for EAFB in accordance with the Comprehensive

Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by

the Superfund Amendments and Reauthorization Act of 1986 (SARA), and the National Oil and

Hazardous Substances Pollution Contingency Plan (NCP). It also states the oversight procedures

for EPA and the State to ensure Air Force compliance with the specific requirements. The FFA

identified 11 site-specific operable units (OUs) and a Base-wide ground-water OU. The Basewide ground-water OU is primarily used to address contaminated ground water that was not

addressed during the investigation of a site-specific OU.

Listing on the NPL and execution of the FFA required the U.S. Air Force to perform a remedial

investigation/feasibility study (RIFFS) to investigate the 12 OUs. In 1993 and 1994, an extensive

RI field program was conducted to characterize conditions at OU-1. The program included

drilling and sampling ofboreholes, installation of ground-water monitoring wells, ground-water

sampling, geotechnical analysis of soil samples, ecological evaluation, assessment of human health

risks, and review and compilation of previous IRP investigations. Collection and laboratory

analysis of soil, ground-water, surface-water, and sediment samples were included in the RI field

program.

A ROD for an interim remedial action (IRA) for OU-1 was signed on 16 May 1995. The

objectives of the IRA were (1) to remediate the deeper soils within the bum-pit area and (2) to

remediate ground-water contamination immediately downgradient from the burn-pit area. The

remediation of the deeper soils within the bum-pit area consists of a soil vapor extraction system

and subsequent treatment by thermal oxidation. The remediation of contaminated ground water

immediately downgradient of the burn-pit area consists of removal of contaminated ground-water

using wells and an existing ground-water recovery trench. Treatment of the contaminated ground

water consists of filtration, air stripping, and activated-carbon adsorption. The treatment system

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was constructed as part of the IRA.

2.3 I_IGltLIGItTS OF COMMUNITY PARTICIPATION

Community relations activities that have taken place at EAFB to date include:

• FFA process. After preparation of the FFA by the USAF, EPA, and SDDENR, the

document was published for comment. The FFA became effective April 1, 1992.

• Administrative Record. An Administrative Record for information was established in

Building 8203 at EAFB. The Administrative Record contains information used to

support USAF decisions. All the documents in the Administrative Record are available to

the public.

• Information repositories. An Administrative Record outline is located at the Rapid City

Library (public repository).

• Community Relations Plan (CLIP). The CRP was prepared and has been accepted by

EPA and the State of South Dakota and is currently being implemented. An update to

this plan will be prepared in 1996.

• Restoration Advisory Board (RAB). The RAB has been formed to facilitate public

input in the cleanup and meets quarterly. In addition to USAF, EPA, and South Dakota

oversight personnel, the RAB includes community leaders and local representatives from

the surrounding area.

• Mailing list. A mailing list &all interested parties in the community is maintained by

EAFB and updated regularly.

• Pact sheet. A fact sheet describing the status of the IRP at EAFB was distributed to the

mailing list addressees in 1992.

• Open house. An informational meeting on the status of the IRP and other environmental

efforts at EAFB was held on May 6, 1993. An open house was held November 16, 1995

in conjunction with the Restoration Advisory Board meeting. Information on the status

of environmental efforts at EAFB was provided at the open house.

• Newspaper articles. Articles have been written for the Base newspaper regarding IRP

activity.

• Proposed Plan. The proposed plan on this action was distributed to the mailing list

addressees for their comments.

A public comment period was held from September 18, 1995 to October 18, 1995, and a public

meeting was held on September 26, 1995. At this meeting, representatives from EAFB answered

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questions about the remedial action. A response to the comments received during this period is

included in the Responsiveness Summary, which is part of this Record of Decision (ROD).

This ROD is based on the contents of the Administrative Record for OU-I, in accordance with

the CERCLA, as amended by SARA, and the NCP. The RIFFS reports and the Proposed Plan for

OU-1 provide information about OU-I and the selected remedy. These documents are available at

the Information Repositories at EAFB and the Rapid City Public Library.

2.4 SCOPE AND ROLE OF RESPONSE ACTION

The FFA identified 11 site-specific OUs and a Base-wide ground-water OU. The 12 operable

units are identified as follows:

OU-I Fire Prolection Training Area

OU-2 Landfills Nos 1 and 6

OU-3 Landfill No. 2

OU-4 Landfill No. 3

OU-5 Landfill No. 4

OU-6 Landfill No. 5

OU-7 Weapons Storage Area

OU-8 Explosive Ordnance Disposal Area (Pramitol Spill)

OU-9 Old Auto Hobby Shop Area

OU- 10 North Hangar Complex

OU-11 Base-wide Ground Water

OU-12 Hardfill No. 1

This ROD documents the selected remedial action (RA) at OU-I and is the fourth ROD for

EAFB. The remedial action objectives (RAOs) are: (1) the cleanup of ground water to regulatory

levels and, for contaminants where regulatory levels are not available, to levels considered safe for

public drinking water, and (2) the cleanup of source area soils to levels that would not pose a

threat of contaminating ground water.

The development of alternatives was conducted under EPA's Presumptive Remedies Approach

[Presumptive Remedies." Policy and Procedures (OSWER Directive 9355.0-47FS); Presumptive

Remedies." Site Characterization and Technology Selection for CERCLA Sites with Volatile

Organic Compounds in Soils (OSWER Directive 9355.0-48FS)]. Using this approach, selecting

an alternative for remediation is streamlined by using preferred technologies based on historical

patterns of remedy selection and EPA's scientific and engineering evaluation of performance data

on technology implementation.

The presumptive remedy stipulates soil vapor extraction (SVE) as the primary remedy for soils

that are contaminated with volatile organic compounds (VOCs). In addition, thermal desorption

is being retained as a secondary source area soil treatment option. The response action, sourcearea soil and ground-water treatment, combines the presumptive remedies for soil with groundwater extraction and treatment to reduce risk associated with the ingestion exposure pathway.

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The area over which remediation goals would be achieved is defined as the area of attainment, and

is based on the RAOs. The area of attainment would include areas within OU-1 which present an

unacceptable risk to human health or the environment.

2.5 SITE CHARACTERISTICS

This section describes the presence and distribution of contaminants at OU-1 as a result of past

activities.

2.5.1 Soils

Organic Contaminants

Organic compounds reported in soil samples from OU-1 include volatile organic compounds

(VOCs), jet fuel, semivolatile organic compounds (SVOCs), pesticides, and dioxins/furans. Total

petroleum hydrocarbon (TPH) concentrations, analyzed as jet fuel, above the State of South

Dakota action level (500 ppm) were reported in 4 surface-soil samples and 11 capillary fringe soil

samples located in and adjacent to the burn pit. Soil which has been impacted by past activities at

OU-1 extends from the surface to the capillary fringe beneath the former FPTA, and within the

capillary fringe from the former FPTA to approximately 800 feet to the south.

In general, the most prevalent organic contaminant in the soil is jet fuel. The State of South

Dakota regulations for petroleum-contaminated soils have been recently revised and effective

December 18, 1995; new risk-based criteria are used to determine if petroleum-contaminated soil

requires removal or treatment. The new regulations establish a three-tiered approach in

determining what action will be taken at petroleum release sites (ARSD Chapter 74:03:13). The

regulations establish Tier 1 action levels for five petroleum related components (benzene,

ethylbenzene, toluene, xylene, and naphthalene) and TPH. Two of the five chemicals (benzene

and ethylbenzene) for which soil action levels have been established by the State were detected in

the soil above their respective action levels in three different borings in the vicinity of the burn pit.

Concentrations of TPH (as jet fuel) in the soil were above the 500 ppm Tier 1 action limit in 12

different soil boring locations in and around the bum pit area. Based on this, a Tier II evaluation

is required. Because pathways and receptors are present, remediation of jet fuel is required.

Also, State guidance concerning the need for installation of monitoring wells at a petroleum

release site (Handbook for Investigation and Corrective Action Requirements for Discharges from

Storage Tanks, Piping Systems, and Other Releases, SDDENR Ground-Water Quality Program,

Version 1.1, December 18, 1995) indicates that monitoring wells will be required at this site.

Inorganic Contaminants

In general, the subsurface-soil samples which contained the highest concentrations of inorganic

compounds were from the former bum-pit area. The source of the inorganic compounds in OU-1

subsurface-soil samples is believed to be from a combination of bum pit activities and

naturally-occurring geologic deposits and soil type. No distinct pattern was observed for the

higher concentrations of inorganic compounds in OU-1 surface-soil samples.

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2,5.2 Sediment

Organic Contaminants

VOCs, SVOCs, and pesticides were reported in sediment samples collected from the drainage

channel both upgradient and downgradient of OU-1, from within the drainage channel at OU-I,

and within Pond 001. Although OU-1 may have contributed to the contaminants in sediment, the

presence of these organic compounds in samples collected upstream of OU-1 indicates that the

primary source of contaminants in sediments is from areas upgradient of OU-1. The highest

concentrations of contaminants were in Pond 001 where sediments are likely to build up over

time. It is not possible to distinguish the exact source of contaminants in the sediments in the

pond. Possible upgradient sources for the organic compounds in sediment samples are the

operations areas along the taxiways and flightlines.

Inorganic Contaminants

Many of the inorganic analytes were reported only once in each of the nine sediment samples with

the exception of cyanide, thallium, and mercury. The source &the inorganic analytes is thought

to be a combination of surface-water runoff from both outside and within OU-1 as well as

naturally-occurring geologic deposits and soil type.

2.5.3 Ground Water

Organic Contaminants

Contaminants were found in ground-water samples from both within and downgradient of the

former FPTA. The most frequently reported organic contaminant in ground-water samples from

OU-1 were VOCs. SVOCs were reported in ground-water samples to a lesser extent• VOCs and

SVOCs in the ground water are a result of historical use of fuels, waste oiIs, and solvents in the

burn-pit area. Seven VOCs, one SVOC, and one pesticide were reported at least once at

concentrations exceeding the Safe Drinking Water Act Maximum Contaminant Level (MCL).

Inorganic Contaminants

Thirteen inorganic compounds were detected in ground-water samples at concentrations which

were above general background levels• However, due to variations in soil type and geologic

deposits, localized high concentrations of inorganic compounds in the EAFB area are common.

Two compounds, manganese and antimony, weie reported at least once at concentrations

exceeding the MCL. Regional and site-specific background results indicate that these two

inorganic compounds naturally occur at levels in ground water that exceed the MCL and their

presence is not thought to be a result of historical activities at OU-1. Arsenic was reported in

four ground-water samples at concentrations of two to six times background from locations

within and downgradient of the burn pit. In general, the'remaining inorganic compounds were

also detected in samples from locations within, and immediately downgradient of, the burn-pit

area. The source of the remaining inorganic compounds is considered to be primarily a result of

historical activities at the FPTA, although some compounds may be a result of the natural

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variations in soil type and geologic deposits•

2.5.4 Surface Water

Organic Contaminants

Three VOCs, one phthalate, and one polynuclear aromatic hydrocarbon (PAH) were reported in

surface-water samples from the drainage channel and Pond 001. The organic compounds

reported in surface-water samples were not reported in soil or ground-water samples from within

OU-1 and are believed to be a result &surface spills outside ofOU-1.

Inorganic Contaminants

Of the inorganic contaminants detected in surface-water samples, arsenic, manganese and nickel

exceeded Federal Ambient Water Quality Criteria (FAWQC) and State Water Quality Standards.

The source of the inorganic analytes in OU-1 surface-water samples is not known, but is

suspected to be from the flightline area, which is upstream and outside ofOU-1.

2.6 SITE RISK SUMMARY

Human Health Risks

Risk Assessment Process

The assessment of human health risks for this OU considered the following topics:

•(1) Chemicals &concern (COCs) in ground-water, surface water, sediment, and soil

samples taken at OU-1;

(2) Current and future land-use conditions;

(3) Potential environmental pathways by which populations might be exposed;

(4) Estimated exposure point concentrations of COCs;

(5) Estimated intake levels of the COCs;

(6) Toxicity of the COCs; and

(7) Uncertainties in the assessments of exposure, toxicity, and general risks.

Noncarcinogenic and carcinogenic risks were calculated for the following five potential exposure

groups:

(1) Current EAFB maintenance personnel mowing grass on-site;

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(2) The future child/adult living on-site who ingests surface Soil;

(3) The future adult living on-site who ingests and showers with shallow ground water;

(4) Future adolescents who are exposed to surface water and sediment through wading; and,

(5) Future adult construction workers who excavate on-site for building residences.

A quantitative risk assessment was performed for the ground water, surface water, soil, sediment,

and air. The risk assessment evaluated potential effects on human health posed by exposure to

contaminants from OU-1. Carcinogenic risks were estimated as the incremental probability of an

individual developing cancer over a lifetime as a result of exposure to a potential cancer-causing

chemical. The acceptable risk range expressed as a probability is one cancer incidence in ten

thousand people to one cancer incident in a million people. This level of risk is also denoted by

1 x 10-4to 1 x 106. Risks within the acceptable risk range may or may not warrant remedial

action depending upon site-specific circumstances. Risks below this range cannot be differentiated

from the background occurrence of cancer in human populations. Risks calculated in a risk

assessment are excess (i.e., over background) cancer risks due to exposure from contaminants.

Noncarcinogenic health risks are evaluated using a hazard index (HI). If the hazard index is less

than or equal to one, the contaminant concentration is considered an acceptable level and

generally assumes that the human population may be exposed to it during a 30-year period

without adverse health effects.

Risk Assessment Results

The risk assessment for OU-I indicated unacceptable risk in the shallow ground water for the

residential exposure scenarios. The chemicals which contributed the majority of the risk in

shallow ground water were VOCs. Of the VOCs, benzene, 1,2-dichloroethane, (1,2-DCA)

1,1-dichloroethylene (i, 1-DCE), 1,2-dichloroethylene (1,2-DCE), 1,1,1-trichloroethane,

perchloroethylene (PCE), trichloroethylene (TCE), and vinyl chloride were identified as being

above their respective MCLs.

The risk assessment indicated that unacceptable risk exists in the soils of the burn-pit area,

primarily from the potential for contaminating the underlying ground water. In order to prevent

future contamination of the ground water, four VOCs were identified for remediation in soils:

benzene, 1,2-DCE, PCE, and TCE. These chemicals were selected for remediation on the basis

of a contaminant transport model. Remediation of jet fuel in the soil at OU-1 is also required

because concentrations of jet fuel (and related components) exceed State of South Dakota

regulations. Risks from exposure to pesticides and dioxins/furans in surface and subsurface soils

at OU- I were well below the acceptable range and do not warrant remediation.

The risk from the contaminants in the sediments and surface water at OU-1 is within the

acceptable risk range. Several compounds were detected in surface water at above the FAWQC,

but the risk to human health from these contaminants is within the acceptable risk range. Because

of the risk being within the acceptable risk range, remediation of these chemicals in surface water

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and sediment is not warranted.

Risk Assessment Conclusions

Remediation of the ground water is warranted based on the risk to human health from ingesting

and contacting contaminated ground water. Remediation of soil is warranted based on the

potential for contaminants in the soil to be transported to the underlying ground water. Actual or

threatened releases of hazardous substances from OU-1, if not addressed by implementing the

response action selected in this Record &Decision (ROD), may present an imminent and

substantial endangerment to public health, welfare, and the environment.

Ecological Risks

An ecological risk evaluation of OU-1 was based on a combination of data and literature reviews,

field and laboratory analyses, analyte evaluation and screening, and preliminary risk screening.

The pertinent findings are summarized below.

A variety of animal species may live, forage, or nest in OU-1 habitats. These species include

various types of invertebrates, amphibians, birds, and mammals. Terrestrial vegetation and soil

faunal communities do not reveal characteristics that indicate chemical-related impacts. This

finding is consistent with the relatively low levels of contaminants in the soil.

Because of the altered natural environment at OU-1, rare, threatened, or endangered species are

unlikely to utilize the area for more than brief, periodic habitat. Due to the low levels of

contaminant concentrations and the identified exposure pathways, the contaminants do not pose

an unacceptable risk to these species. In addition, the limited contact these species would have

with the OU- 1 area ensures unacceptable risk to a single individual will not occur.

Findings of the RI indicate that the contaminants at OU-I are not altering the ecology to

unacceptable levels. A Base-wide ecological risk assessment will be conducted as part ofOU-11,

and OU-1 will be included in this Base-wide evaluation.

2.7 DESCRIPTION OF ALTERNATIVES

Presumptive Remedies: Site Characterization and Technology Selection for CERCLA Sites with

Volatile Organic Compounds in Soils (OSWER Directive 9355,0-48FS) was the basis of the

streamlined feasibility study (FS). This presumptive remedy was incorporated into the remedial

action at OU-1 to develop the following alternatives.

* Alternative I - No Further Action

• The no further action alternative represents the baseline condition at OU-1 and

refers to taking no further action at the operable unit.

• Alternative 2 - Source Area Soil Treatment with Ground-water Containment

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• Continued operation of the interim remedial action (IRA).

• Installation and use of additional SVE wells, ground-water wells and/or collection

trenches to contain the existing soil and ground-water contamination.

• Soil gas and contaminated ground water would be treated at the IRA treatment

plant. The water effluent will either be discharged to a surface water drainage,

pumped to the Base waste-water treatment plant, or injected underground.

• Long-term maintenance and monitoring.

• Institutional controls (access restrictions and deed restrictions).

• Alternative 3 - Source Area Soil Treatment and Ground-water Treatment

• Same as Alternative 2 with additional ground-water wells and trenches.

This alternative is the same as Alternative 2 except that the ground-water removal system would

be designed to not only contain the contaminated ground water, but to permanently lower the

contaminant concentrations in the ground water to the levels listed in Table 2-1.

2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

The analysis of altematives coupled with the use of the presumptive remedy combine for a

narrower range of feasible approaches to address remedial activities at OU-1.

The remedial action objectives for OU-1 are as follows:

• Achieve the ground-water clean-up goals set forth in Table 2-1.

• Achieve the soil clean-up goals set forth in Table 2-2.

The area of attainment is defined as the area which will achieve the remedial action objectives

after remediation is completed. The areal extent of the source-area soil attainment area for OU-1

is based on reported concentrations of chemicals of concern and is shown in Figure 2-4. The

ground-water attainment area was based on MCLs for the reported chemical concentrations at

OU-1 and is shown in Figure 2-5.

Pursuant to Section 40 CFR 300.430(e)(9)(iii), the remedial action to be implemented should be

selected based upon consideration of nine evaluation criteria. These criteria are as follows:

1. Overall protection of human health and environment.

2. Compliance with applicable or relevant and appropriate requirements (ARARs).

3. Long-term effectiveness and permanence.

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4. Reduction of toxicity, mobility, or volume of contamination.

5. Short-term effectiveness.

6. Implementability.

7. Cost.

8. State acceptance.

9. Community acceptance.

The following sections provide a brief review and comparison of the remedial alternatives

according the EPA's evaluation criteria.

2.8.1 Overall Protection of Human Health and the Environment

The assessment of this criterion considers how the alternatives achieve and maintain protection of

human health and the environment.

Alternative 1 does nothing to reduce risk levels at OU-1. Alternatives 2 and 3 both reduce the

risk of source-area soils contaminating the underlying aquifer and address ground-water

remediation. Alternatives 2 and 3 would remediate ground water to levels at or below MCLs.

However, the primary goal of Alternative 2 is to only contain contaminated ground water. Under

Alternative 2, the aquifer may eventually be restored to the levels listed in Table 2-1. It would

take approximately 10-15 years longer for the ground water to be remediated to levels listed in

Table 2-1 under Alternative 2 as compared to Alternative 3.

2.8.2 Compliance with ARARs

Alternatives are assessed under this criterion in terms of compliance with ARARs. Applicable

requirements include cleanup standards, standards of control and other substantive environmental

protection requirements, criteria or limitations promulgated under Federal or State of South

Dakota laws that specifically address a hazardous substance, pollutant, contaminant, remedial

action, location or other circumstances at a CERCLA site.

Relevant and appropriate requirements address problems that do not specifically address a

hazardous substance, pollutant, or remedial action Rather, these requirements address problems

or situations that are similar to those encountered at a particular CERCLA site, and therefore,

these requirements are suited for use at the site because of these similarities. ARARs are grouped

into these three categories:

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• Chemical-Specific ARARs are health or risk-based numerical values or

methodologies which, when applied to site-specific conditions, result in

establishment of the amount or concentration that may be found in, or discharged

to, the environment.

• Location-Specific ARARs restrict the concentration of hazardous substances or

the conduct of activities solely because they are in specific locations such as flood

plains, wetlands, historic places, and sensitive ecosystems or habitats.

• Action-Specific ARAKs are usually technology or activity-based requirements or

limitations on actions taken with respect to hazardous wastes.

TABLE 2-1

OU-1 Clean-up Goals

Ground Water 0ag/L)

Analyte Clean-up Goal Basis

1,2-Dichloroethane (1,2-DCA) 5.0 MCL

1,1-Dichloroethylene (1,1-DCE) 7.0 MCL

1,2-Dichloroethylene (1,2-DCE) 70.0 MCL

1,1,1-Trichloroethane 5.0 MCL

Benzene 5.0 MCL

Tetrachloroethylene (PCE) 5.0 MCL

Trichloroethylene (TCE) 5.0 MCL

Vinyl Chloride 2.0 MCL

TPH 10,000 State Regulation

Ethylbenzene 700 State Regulation

Toluene 1,000 State Regulation

Xylene 10,000 State Regulation

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TABLE 2-2

OU-1 Clean-up Goals

Soils (_tg/kg)

Clean-up Model

Analyte Goal Estimates °l Basis

1,2-Dichloroethylene (1,2-DCE) 41 41A Ground water protection

Benzene 10_2) 2.5 Ground water protection

Tetrachloroethylene (laCE) 10 10.5 Ground water protection

Trichloroethylene (TCE) 10(27 3.3 Ground water protection

JP-4 500,000 (3_ - State Regulation

Toluene 15,000 (3_ - State Regulation

Ethylbenzene 10,000 °) - State Regulation

Xylene 300,000 (3) - State Regulation

Naphthalene 25,000 (3_ - State Regulation

°)Note: Basedon SUMMERSModel(Summers,1980)

(2:'Note:When the modelestimatesare less than standarddetectionlimits,remediatienctean-upgoalswillbe

basedon standard.detectionlimits.

O_Note:Stateof SouthDakotaRemediationCriteriafor PetroleumContaminatedSoil,Tier 1 actionlevelsat

petroleumreleasesites whichwouldrequirea correctiveactionplan orTier 2 analysis

(ARSDChapter74:03:33).

A summary evaluation of Federal and State ARARs pertinent to this remedial action is provided in

Table 2-3 at the end of Section 2.0 and a narrative discussion of compliance with ARARs is

provided below for the alternatives considered.

Alternative 1 (No Action):

Since there are no remedial activities currently being conducted and none are proposed under this

alternative, there are no remediation ARARs applicable. The No Action alternative does not

comply with CERCLA ARARs as a stand-alone action. The ground water at the site would

remain contaminated•

Alternatives 2 and 3 (Source Area Soil Treatment with Ground-water Containment/Treatment):

The Safe Drinking Water Act will be complied with by extracting and treating ground water so

that contaminant concentrations in the shallow aquifer are below the MCLs. State ground-water

quality standards (ARSD Chapter 74:03:15) will also be complied with. However, compliance

with MCLs will take approximately 10-15 years longer under Alternative 2 as compared to

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Alternative 3. The discharge of the treated ground water will comply with State of South Dakota

discharge requirements (ARSD Chapter 74:03:17 for indirect or direct discharges into surface

waters and ARSD Chapter 74:03:13 for reinjection of discharged water underground). State

discharge requirements comply also with Federal requirements of the Clean Water Act (CWA),

The proposed SVE system will reduce the concentrations of JP-4 in the soils to levels in

compliance with South Dakota Petroleum-Contaminated Soils regulations (ARSD Chapter

74:03:33).

Treatment-process residuals such as spent carbon will be disposed of in a manner complying with

State and Federal solid waste disposal restrictions (40 CFR 268). Construction of the collection

trench will not degrade onsite wetlands and therefore will comply with the Executive Order on

Protection of Wetlands and Section 404 of the CWA. Air and water discharges from the IRA

treatment facility will comply with South Dakota Air Pollution Control Regulations (ARSD

Chapter 74:26) and water discharge permit rules and water quality standards as stated above.

2.8.3 Long-Term Effectiveness and Permanence

The assessment of this criterion considered the long-term effectiveness of alternatives in

maintaining protection of human health and the environment after response action objectives have

been met.

Alternative 1 does not provide long-term effectiveness in achieving the remedial action objectives

established for this site. No further controls for the OU would be developed under this

alternative.

For Alternatives 2 and 3, residual risk levels would be low enough that source-area soils would

not pose a risk to ground water. MCLs would be met for ground water. However, it would take

approximately 10-15 years longer for the ground water to be remediated to the MCLs under

Alternative 2 as compared to Alternative 3. The ground-water collection system for Alternative 2

would be designed to preclude further transport &the ground-water contamination. The groundwater collection system for Alternative 3 would be designed to also remediate the ground water

to the levels listed in Table 2-1. Long-term monitoring of vapor extraction rates and

concentrations would be necessary to maintain proper system operation•

2.8.4 Reduction of Toxicity, Mobility, and Volume Through Treatment

The assessment of this criterion involves considering the anticipated performance of specific

treatment technologies an alternative may employ.

No reduction of potential source area chemicals with respect to toxicity, mobility, or volume

would be achieved with Alternative 1. Alternatives 2 and 3 would reduce the volume of VOCs in

source-area soils to levels protective of ground-water quality. The ground-water collection

system would reduce the mobility of the ground-water contamination by preventing further

downgradient movement. The removal and treatment of contaminants would also reduce the

volume of contaminated ground water. The volume ofcontamlnated ground water would be

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reduced faster under Alternative 3 as compared to Alternative 2.

2.8.5 Short-Term Effectiveness

The assessment of this criterion considers the effectiveness of alternatives in maintaining

protection of human health and the environment during the construction of a remedy until

response action objectives have been met.

Alternative 1 does not provide any short-term effectiveness in reducing potential threats from this

site to human health or the environment. Since no construction activities would take place, risk

from remedial action would not exist.

Adverse environmental impacts due to the construction and implementation of Alternatives 2 and

3 are expected to be minor. Construction would comply with OSHA requirements to help

eliminate the risk to construction workers. Community risk is expected to be minimal due to low

levels of contaminants in the surface soil and dust control measures would be implemented.

2.8.6 Implementability

The assessment of this criterion considers the administrative and technical feasibility of

implementing the alternatives and the availabilityof necessary goods and services for

implementation of the response action

There is nothing to implement under Alternative 1. Alternatives 2 and 3 require no special or

unique activities and could be implemented using locally available materials and contractors. Any

implementability concerns were addressed during the IRA.

2.8.7 Cost

The assessment of this criterion considers the capital and operation and maintenance (O&M) costs

associated with each of the alternatives. Alternatives are evaluated for cost in terms of both

capital costs and long-term O&M costs necessary to ensure continued effectiveness of the

alternatives. Capital costs include the sum &the direct capital costs (materials and labor) and

indirect capital costs (engineering, licenses, permits). Long-term O&M costs include labor,

materials, energy, equipment replacement, disposal, and sampling necessary to ensure the future

effectiveness of the alternative. The objective of the cost analysis is to evaluate the alternatives

based on the ability to protect human health and the environment for additional costs that may be

incurred. A summary of the costs for each alternative is as follows:

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Alternative No. 1 (No Action)

Total Capital Costs $0

Total Annual (Sampling/Analysis) Costs $0

30-Year Present Value for Annual Costs $0

Annual Cost = $0

Years = 30

Discount Rate = 5%

TOTAL 30-Year Present Value $0 =

Alternative No. 2 (Source Area Soli Treatment and Ground-water Containment)

Total Capital Costs $782,000

Total Annual (Sampling/Analysis/O&M) Costs $150,000

30-Year Present Value for Annual Costs $2,306,000

Annual Cost = $25,000

Years = 30

Discount Rate = 5%

TOTAL 30- Year Present Value $3,088,000

Alternative No. 3 (Source Area SoU Treatment and Ground-water Treatment)

Total Capital Costs $986,000

Total Annual (Sampling/Analysis/O&lVD Costs $96,000

30-Year Present Value for Annual Costs $1,479,000

Annual Cost = $25,000

Years = 30

Discount Rate = 5%

TOTAL 30-Year Present Value $2,465,000

The majority of the costs for Alternatives 2 and 3 are from long-term monitoring and

maintenance. The capital costs for Alternative 3 are approximately $204,000 greater than the

capital costs for Alternative 2. This is due to the additional ground-water extraction wells and/or

trenches needed to remediate the ground water under Alternat{ve 3 rather than contain the ground

water under Alternative 2. Because Alternative 2 will operate approximately 10-15 years longer

than Alternative 3, the long-term monitoring and maintenance costs are much greater for

Alternative 2. These additional long-term monitoring and maintenance costs are much greater

than the additional capital costs to remediate the ground water under Alternative 3. Alternative 3

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is the most cost-effective alternative.

2.8.8 State Acceptance

The assessment of this criterion considered the State's preferences for or concerns about the

alternatives

The State concurs with the selected remedy. The State provided comments on the remedial

investigation, feasibility study, and Proposed Plan. In accordance with the requirements of the

NCP, the State of South Dakota was also provided the opportunity to review and comment on

the ROD. As a result of that review and after incorporating adequate responses to the comments

into the respective documents, the State concurred with the remedy.

2.8.9 Community Acceptance

Comments offered by the public were used to assess the community acceptance of the proposed

alternative. The community expressed their concerns about the selected remedy during the public

comment period. The questions and concerns of the community are discussed in detail in the

Responsiveness Summary, which is Appendix B of the ROD. Community members did not

express any concerns about the Proposed Plan which would require a change in the chosen

alternative.

2.9 SELECTED ALTERNATIVE

Based on the requirements of CERCLA, comparative analysis of the nine criteria, public

comments, and in consultation with EPA and the State, the Air Force has determined that the

selected alternative is Alternative 3, Source Area Soil Treatment and Ground-water Treatment.

This alternative includes institutional controls in conjunction with physical modification of the OU

to reduce potential risk. Five-year reviews of the remedy will be required because contaminants

at OU-1 will remain above health-based levels following completion of installation of the

extraction components of the remedy. Major components of Alternative 3 are:

• Continued operation of the IRA which consists of(l) SVE to remediate a portion

of the source area soils and (2) ground-water wells and an existing collection

trench to remove contaminated ground water near the source area.

• Installation and use of additional SVE wells, ground-water wells and/or collection

trenches.

• Soil gas and contaminated ground water would be treated at the IRA treatment

plant. The water effluent will either be discharged to surface water, injected

underground, o.rdischarged to the Base waste-water treatment plant.

• Implementing institutional controls (deed and land use restrictions) to restrict the

future use of the area while the remedy is being implemented.

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• Providing for long-term ground-water monitoring at the OU to identify "

development of future risks associated with the OU. Providing long-term

maintenance of the remedial actions taken at the OU.

Each of these items is discussed below.

Continued Operation of the IRA

The IRA consisted of(l) SVE to remediate a portion of the source area soils and (2) groundwater wells and an existing collection trench to remove contaminated ground water near the

source area. The IRA also included the construction of a treatment plant for the treatment of the

soil gas and contaminated ground water. The IRA will be operated and the additional SVE wells,

ground-water wells, and collection trenches described below will be added to the system.

SVE Wells, Ground-Water Wells and/or Trenches

The objective of this alternative is to decrease soil contaminant concentrations within the burn-pit

to the levels listed in Table 2-2 and to remediate the shallow aquifer to levels listed in Table 2-1.

The area targeted for SVE is the bum-pit area (Figure 2-4). Additional SVE wells will be placed

in the burn-pit area to remove soil contamination that was not addressed in the IRA. The

number and placement of the SVE wells will be further evaluated during the design.

Ground-water wells and/or collection trenches will be installed at OU-1 to remediate the

contaminated shallow aquifer at OU-1 to the levels listed in Table 2-1. The number and

placement of wells and/or trenches will be evaluated during the design. The ground-water wells

and trenches will collect and remove contaminated ground water at OU-1. The aquifer is

expected to be remediated in 10-15 years.

Treatment

Extracted soil gas, condensate from the SVE wells, and ground water removed by wells and

trenches will contain both VOCs and petroleum hydrocarbons. These contaminants will be

treated at the treatment plant built for the IRA. Treatment of the soil gas and contaminated

ground water consists of filtration, air stripping, activated-carbon adsorption, and thermal

oxidation.

The water effluent from the treatment plant is expected to be discharged into a drainage which

flows into Pond 001. The effluent will be monitored prior to discharge to determine the

effectiveness of the treatment system. Effluent discharge standards and monitoring will be

determined during the design phase and are subject to State and EPA reviews and approvals.

Underground injection or discharge to the Base waste-water treatment plant may be chosen as the

discharge option based on the allowable discharge standard. The expected surface water

discharge will comply with the requirements of the Clean Water Act. Off-gas from the thermal

oxidizer will be monitored to ensure compliance with Federal, State, and local requirements

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undertheprovisionsoftheCleanAirAct.

Institutional Controls

Institutional controls will be implemented to prevent human exposure to contaminated soil and

ground water. These controls wilt include: (1) issuing a continuing order to restrict on-site

worker access to contaminated soil, and to restrict or control temporary construction activities

unless proper protective equipment is worn; (2) filing a notice with the State to recommend denial

of water appropriation permit applications to install ground-water wells within the area of

contamination and any area which may be effected by potential contaminants; (3) filing a notice to

the deed detailing the restrictions of the continuing order and ground-water well restrictions; and

(4) a covenant to the deed in the event of property transfer.

Continuing order requirements will be in effect as long as the property is owned by Ellsworth

AFB and the remedial action has not reached remediation goals. In the case of the sale or transfer

of property within OU-1 by the United States to any other person or entity, the Air Force will

place covenants in the deed which will restrict access and prohibit disturbance of contaminated

soils or the remedial action without approvaI of the United States. These covenants will be in

effect until removed upon agreement of the State of South Dakota, the US. Environmental

Protection Agency, and the U.S. Air Force or their successors in interest. The Air Force will also

include in the deed the covenants required by section 120(h)(3) of the Comprehensive

Environmental Response, Compensation and Liability Act (CERCLA), which include (1) a

warranty that the United States will conduct any remedial action found to be required by law after

the date of the transfer; (2) a right of access in behalfofEPA and the Air Force or their

successors in interest to the property to participate in any response or corrective action that might

be required after the date of transfer. The right of access referenced in the preceding sentence

shall include the State of South Dakota for purposes of conducting or participating in any

response or corrective action that might be required after the date of transfer.

Long-Term Monitoring and Maintenance

A maintenance program would be established to ensure the long-term integrity of the removal and

treatment system. The maintenance program would include development of standard operating

procedures (SOPs) to provide for inspections, repairs, and leak response actions.

A long-term monitoring program will be developed and implemented during remedial action and

is subject to approval of both EPA and SDDENR. Contaminant concentrations from the

treatment plant vapor stream and treated ground water will be monitored to evaluate the

effectiveness of the system in removing VOCs from the contaminated media. Contaminant

concentrations in the burn-pit area and in the ground water will also be monitored. Continued

analysis and monitoring of the ground-water remedial action system performance will be

conducted to determine if the remediation system is approaching an asymptotic level due to

physical limitations of the site, or the benefits of the remedial action no longer justify long-term

operation of the system. Remediation goals and the remedial alternative will be re-evaluated at

that time.

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This alternative will meet the remedial action objectives and reduce the potential risk at OU-1 by

treating contaminated ground water to levels considered safe for public drinking water and by

preventing future contamination of the shallow aquifer by reducing the volume of contaminants in

the soil above the shallow aquifer. This will be achieved by the installation of ground-water wells

and/or collection trenches, installation of SVE wells, and treatment of removed ground water and

soil vapor.

Alternative 3 would achieve significant risk reduction at the OU by treating ground water to

reduce contaminant concentrations to below the MCLs. The selected alternative will be

protective of human health and the environment and will comply with ARARs.

2.10 STATUTORY DETERMINATIONS

The selected remedy meets the statutory requirements of Section 121 of CERCLA as amended by

SARA. These requirements include protection of human health and the environment, compliance

with ARARs, cost effectiveness, utilization of permanent solutions and alternative treatment

technologies to the extent practicable. The selected remedy represents the best balance of

tradeoffs among the alternatives considered, with respect to pertinent criteria, given the scope of

the action.

The manner in which the selected remedy meets each of these requirements is discussed in the

sections below.

2.10.1 Protection of Human Health and the Environment

The selected remedy addresses health and environmental issues that were identified in the OU-1

RI report. Specifically, the alternative:

• Reduces contaminant concentrations in ground water to MCLs.

• Reduces the potential infiltration of contaminants to the ground water.

• Prevents unauthorized access and use of the area while remediation is taking place

thereby preventing exposure to contaminants by Base personal and potential future

residents. ' ......

• Provides for long-term monitoring of ground water to identify potential future

risks associated with OU-1.

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2.10.2 Compliance with ARARs

Alternative 3 will meet Safe Drinking Water Act MCLs and South Dakota Ground Water Quality

Standards (ARSD Chapter 74:03:15). Treated discharge water will comply with the requirements

of an NPDES permit. The proposed SVE system will reduce concentrations of JP-4 to comply

with South Dakota Petroleum-Contaminated Soils regulations. Additional information about

ARAR compliance is contained in Section 2.8.2.

2.10.3 Cost Effectiveness

The selected remedy has been determined to provide overall effectiveness proportional to its costs

and is therefore considered cost effective The presumptive remedy process insures cost effective

remedies are chosen. The estimated costs of the selected remedy are less than the costs

associated with a similar alternative that utilizes only ground-water containment. The selected

remedy provides a higher degree of protectiveness at a lower cost than the containment

alternative. All the technologies included in the remedy are readily implementable and have been

widely used and demonstrated to be effective.

2.10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to

the Extent Possible

The selected remedy represents the maximum extent to which permanent solutions and treatment

technologies can be utilized in a cost-effective manner for OU-1 EPA has established that SVE

has proven effective in remediating soils containing VOCs. This alternative prevents unauthorized

access and provides for long-term ground water monitoring to detect movement of chemicals

from the area. A review wilt be conducted no less often than every five years after the signing of

the gOD to ensure the remedy continues to provide adequate protection of human health and the

environment

2.10.5 Preference for Treatment as a Principal Element

Treatment of soil within the former FPTA andcontaminated ground water satisfies the statutory

requirement of treatment as a principal element.

2.11 DOCUMENTATION OF SIGNIFICANT CHANGES

The selected action is the same as the preferred alternative presented in the Proposed Plan for

OU-1 remedial action. There have been no changes relative to the Proposed Plan.

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3.0 LIST OF ACRONYMS AND ABBREVIATIONS

1,2-DCA: 1,2-Dichloroethane

1,1-DCE: 1,1-Dichloroethylene

1,2-DCE: 1,2-Dichloroethylene

ACC: Air Combat Command

ARARs: Applicable or Relevant and Appropriate Requirements

ARSD: .Administrative Rules of South Dakota

CERCLA: Comprehensive Environmental Response, Compensation and Liability Act

CFR: Code of Federal Regulations

COC: Chemicals of Concern

CRP: Community Relations Plan

CWA: Clean Water Act

EAFB: Ellsworth Air Force Base

EPA: Environmental Protection Agency

FAWQC: Federal Ambient Water Quality Criteria

FFA: Federal Facilities Agreement

FPTA: Fire Protection Training Area

FS: Feasibility Study

IRA: Interim Remedial Action

IRP: Installation Restoration Program

JP-4: Jet Propulsion Fuel Number Four; contains both kerosene and gasoline fractions.

MCL: Maximum Contaminant Levels

gg/kg: Micrograms per kilogram

gg/L: Micrograms per liter

NCP: National Oil and Hazardous Substances Contingency Plan

NPDES: National Pollutant Discharge Elimination System

NPL: National Priorities List

O&M: Operation and Maintenance

OSHA: Occupational Safety and Health Administration

OSWER: Office of Solid Waste and Emergency Response

OU: Operable Unit

PAIl: Polynuclear Aromatic Hydrocarbon

PCE: Perchloroethylene; liquids used in degreasing or paint removal

ppm: Parts per Million

RA: Remedial Action

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Final Record of Dec&ion Operable Unit 1

Ellsworth Air Force Base, South Dakota

RAB: Restoration Advisory Board

RAO: Remedial Action Objective

RI/FS: Remedial Investigation/Feasibility Study

ROD: Record of Decision

SARA: Superfund Amendments and Reauthorization Act

SDDENR: South Dakota Department of Environment and Natural Resources

SOP: Standard Operating Procedures

SVE: Soil Vapor Extraction

SVOC: Semivolatile Organic Compound

TCE: Trichloroethylene

TPH: Total Petroleum Hydrocarbon

USA/: United States Air Force

VOC: Volatile Organic Compound

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F..kPROJt6037884k._'_OU1.ROD_FINALlOUIROD.FlVL April 1996
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Final Record of Decision Operable Unit 1

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APPENDIX A

FIGURES
815 33 iiiii

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1_ _om_A_'_ SOUTH DAKOTA

WYOMING I " Q ' "_'-

ELLSWORTH AFB

........2.......,,,,,,.._o.:..__J ................

D 5 10

I P_ 1

Scole ;n U_les

< APPROXIMAT[

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o'. AIR FORCE ELLSWO RTH BASE ELLSWORTHAF'B AREALOCATIONMAP

= _i PROJECT MGR DESIC;NED BY DRAWN BY CHECKED BY S DATE

_1 MRG SHOWN OCT95 I 60378.85 I 2-1
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i

INSTALLATION BOUNDARY

WEAPONS

STORAGE

! 0U-8 !

j . ...., OU-3

DEBRIS -- _ BURIAL

ST. _ AREA

_/ ---=- I _2_. .ou_,._, -- _ARNOLI AREA I

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o 1200 2400 _

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LEGEND J-hi •

OPERABLE UNITS OU--1 HOUSINe-%.

OU-1 FIRE PRQ'TECTION TRAINING

AREA (FT-01) _,__

0U-2 LANDFILLS 1 & 6 (LF-02) OU-2

OU-3 LANDFILL 2 (LF-O3) INDUSTRIAL OU-4 LANDFILL 3 (LF-04)

_ OU-5 LANDFILL 4 (LF-05) GATE

OU-6 LANDFILL 5 (LF-O6)

OU-7 LOW LEVEL RAOIAT{ON WASTE BURIAL AREA (RW-07)

OU-8 EXPLOSM[ ORDNANCE DISPOSAL AREA & PRAMITOL SPILL (SB-11)

/ OU-9 OLD AUTO HOBBY SHOP AREA (0T-15)

OU-lO NORTH HANGAR COMPLEX (ST-19) O

/ OU-I I BASEWIDE GROUND WATER

_ 0°-,2,AROF0.,,LL, o,

N w

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_-_ _ ELLSWORTH ELLSWORTHAFB SITELOCATIONMAP :_ AIR FORCE BASE RAPID{:flY,SOUTH _OTA

Zcn

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815 35

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BURN PIT AREA _ •

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SCALE ' ' ' SURFACE DRAINAGE

EPA lggl. BURNPIT HISTORICALAREASFROMAERIALPHOTOCRAPHS19, 52-1gg2

ELLSWORTI-I ELLSWORTHAFB 1 SITEAREA

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MGL AS SHOWNI OCT g5 I 60378.84 2-3
8]5 36 --

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;,_=_7_X_ / REA 0 A AINM_/N_I

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,

.

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I_ , _AR_99`3R,S OFATTA,NMENT OL

_ _ __ * i_2:1__' _ :)"r'eJ_°'_"I BOR,NG LOCAT,ONS

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o= _ _"_" (_)s_0,_ (;_ _N LI BORING LOCATION .

_ \\ _ \ _[_'_3' _0o' 0 _,

o _ ,,_ \\ _ \ \ \" ,_ _ I

_, _ TITLE: FIGURE: DSTAFF T WN BY: APP'DR :

_, _ ELLSWORTH AREA OF ATTAINMENT FOR 2-4 AIR FORCE BASE SOURCE-AREA SOILS DATE: PJT NO:

MAR 96 60378.8_
815 371

r I

I o' _ .- GROUN%-_--_ER, 1 \ _ / AREAOF A?iA"i_IM/ENT-_

= C

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t \ \ _///'/_/'/_'7"//_ I _.Pg_ BORING LOCATIONS

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/.

=2, _ TITLE: FIGURE: DWN BY: APP'D:

_ _ STAFF TR

_! AI ELL R F SWOR ORCE BASE TH AREA OF ATTAINMENT FOR 2--5

_=_' GROUND WATER DATE: PJT NO:

_ MAR 95 60378.8,_
Final Record of Decision Operable Unit 1

- " Ellsworth Air Force Base, South Dakota iAPPENDIX B

RESPONSIVENESS SUMMARY

F._PRO..q60178841FSqOU1-RODhV_IAL}OU1ROD.FNL April 1996
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Final Record of Decision Operable Unit 1

;." Ellsworth Air Force Base, South Dakota

Responsiveness Summary

Remedial Action at Operable Unit One

Ellsworth Air Force Base, South Dakota

I. Overview

The United States Air Force (USAF) established a public comment period from August 8 to

October 16, 1995 for interested parties to review and comment on remedial alternatives

considered and described in the Proposed Plan for Operable Unit One (OU-1). The Proposed

Plan was prepared by the USAF in cooperation with the U.S. Environmental Protection Agency

(USEPA) and the South Dakota Department of Environment and Natural Resources (SDDENR).

The USAF also held a public meeting at 6:30 p.m. on September 26, 1995 in the 28th Bomb Wing

Auditorium at Ellsworth Air Force Base (EAFB) to outline the proposed remedy to reduce risk

and control potential hazards at Operable Units 1, 2, and 4.

Some of the public comments pertained to the selected remedies in the Proposed Plans for all the

operable units. Rather than attempting to separate out the comments which pertained to an

individual operable unit, one Responsiveness Summary was prepared to address all the comments

for all the operable units.

The Responsiveness Summary provides a summary of comments and questions pertaining to OU1, received from the community at the public meeting and during the public comment period, as

well as the USAF's responses to public comments.

The Responsiveness Summary is organized into the following sections:

• Background on Community involvement

• Summary of Comments and Questions Received During the Public Comment

Period and USAF Responses

• Remaining Concerns

The selected remedy for OU-1 is alternative 3, source area soil and ground-water treatment,

which includes the following major components:

• Continued operation &the interim remedial action (IRA) which consisted of

contaminated ground-water removal, soil vapor extraction (SVE), and treatment;

• Installation of additional SVE wells within the historical bum-pit area to be added

to the existing IRA SVE system;

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Final Record of Decision Operable Unit 1

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• Removal of contaminated ground water using additional ground-water wells and

collection trenches to be added to the IRA ground-water recovery system;

• Treatment of ground water at the existing IRA treatment plant;

• Institutional controls for the area;

• Long-term monitoring; and,

• Long-term operation and maintenance of equipment.

2. Background on Community Involvement

On August 30, 1990 EAFB was listed on the USEPA's National Priorities List (NPL). A Federal

Facilities Agreement (FFA) was signed in January 1992 by the Air Force, EPA, and the State and

went into effect on April 1, 1992. The FFA establishes a procedural framework and schedule for

developing, implementing, and monitoring appropriate response actions for EAFB.

Community relations activities that have taken place at EAFB to date include:

• FFA process. After preparation of the FFA by the USAF, EPA, and SDDENR,

the document was published for comment. The FFA became effective April 1,

1992.

• Administrative Record. An Administrative Record for information was

established in Building 8203 at EAFB The Administrative Record contains

information used to support USAF decision-making All the documents in the

Administrative Record are available to the public.

• Information repositories. An Administrative Record outline is located at the

Rapid City Library (public repository)

• Community Relations Plan (CRP). The CRP was prepared and has been

accepted by EPA and the State of South Dakota and is currently being carried out.

An update to this plan will be prepared in 1996.

• Restoration Advisory Board (RAB). The RAB has been formed to facilitate

public input in the cleanup and meets quarterly. In addition to USAF, EPA, and

South Dakota oversight personnel, the RAB includes community leaders and local

representatives from the surrounding area.

• Mailing list. A mailing list of all interested parties in the community is maintained

by EAFB and updated regularly.

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• Fact sheet. A fact sheet describing the status of the IRP at EAFB was distributed

to the mailing list addressees in 1992.

• Open house. An informational meeting on the status of the IRP and other

environmental efforts at EAFB was held on May 6, 1993. An open house was held

November 16, 1995 in conjunction with the Restoration Advisory Board meeting.

Information on the status &environmental efforts at EAFB was provided at the

open house.

• Newspaper articles. Articles have been written for the base newspaper regarding

IRP activity.

The Proposed Plan for this remedial action was distributed to the mailing list addressees for their

comments. Additional copies of the Proposed Plan were available at the September 26, 1995

public meeting. A transcript of comments, questions and responses provided during the public

meeting was prepared.

3. Summary of Comments and Questions Received During the Public Comment

Period and USAF Responses

Part I - Summary and Response to Local Community Concerns

Review of the written transcript of the public meeting did not indicate community objections to

the proposed remedial action. No written comments were received during the public comment

period.

The majority &the comments received during the public meeting for OUs 1,2 and 4 were in the

form &questions about the remedial investigation findings, the remedial action; i.e., what would

be done, how it would be done, and what effects the action might have. In addition, one question

addressed purchase of off-Base property. Representatives &the USAF were available to provide

answers to the questions and also provided an overview presentation during the meeting to

describe the proposed actions. The following are questions and responses pertaining to OU-1.

For questions and responses pertaining to OU-2 and OU-4, refer to the Records of Decision for

these OUs.

Part H - Comprehensive Response to Specific Technical, Legal and

Miscellaneous Questions

The comments and questions below have been numbered in the order they appear in the written

transcript of the September 26, 1995 public meeting.

Comment 1. Jan Deming

Asked about whether the stream running from the northeast to the southwest in OU-1

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Final Record of Decision Operable Unit 1

Ellsworth Air Force Base, South Dakota

was contaminated, or was transporting contaminants.

Response 1: Evidence of jet fuel and pesticides were found in the sediments. The human health

and ecological risk assessments indicated that there was no unacceptable risk to

human and ecological receptors. The storm drains were deferred to OU- t 1 to

allow additional investigation of the ecological conditions on the Base. The

oil/water skimmer in Pond 001 will remove any contamination floating on the pond

surface ira fuel spill were to occur upstream of the OU. The monthly NPDES

sampling for a range &chemicals helps ensure that no contamination is going offBase.

4. Remaining Concerns

Based on review of the transcript of the oral comments received during the public meeting, there

are no outstanding issues associated with implementation of the proposed remedial action.

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